How to list all records in doctype linked in child table

now iam working on shipping rate doctype
the shipping rate is by state every state have it’s price
so now i have a
1- doctype called states contain two fields Country linked to Country Doctype and State
2- doctype called Table Linked to price list table contain two Fields State – Link to Country and State (doctype) and Price – Currency
3-doctype called shipping Rates have this fields
Price List title – Data
Date — Date
Country – linked to Country Field in states Doctype
Price List Table – Table Linked to price list table (doctype)
so i want once user choose the country
the Child table Called price list table sort All Sates in the Chosen Country